ifelse and piecewise function

I am a novice user of "R" and  I'm learning with R version  2.8.1,  
using
WinEdt_1.8.1, under Widows Vista Home Version.

## The test function below, from a vector input, returns vector  
values:
#   and it contains an "ifelse"statement
TEST<- function(x) {
low<- -x^2
up<-   x^4
ifelse(x>=0,up,low )
                  }
u<- seq(-1,1,0.5)
TEST(u)
###########################################################
# #The following function, also containing "ifelse", returns correct
individual values
#  (confirmed independently from another program).
#  Vector input, however, generates the following message:
#  "In if (is.finite(lower)) { :the condition has length > 1 and  
only the
first element
#   will be used"
#  And, in fact, correct multiple values are not returned.
########################################################
ASEPF<- function(y, theta, sigma, alpha, kappa){

loww<-((theta - y)/(sigma* kappa))^alpha

upp<- (kappa *(y - theta)/sigma)^alpha

k<- 1/(1 + kappa^2)

a<- 1/alpha

integrand<- function(y){y^(a-1)* exp(-y)/gamma(1/alpha)}

GL<- integrate(integrand, lower = loww, upper= Inf)$value

GU<- integrate(integrand, lower = upp,  upper= Inf)$value
ifelse(y>=0,1 - k*GU, (kappa^2) *k * GL)
                                              }
ASEPF(u,0,1,2,0.5)
Could someone kindly give me some advice on how to
rewrite the function ASEPF so that it returns a vector of values?